Various processes and catalysts exist for the homopolymerization or copolymerization of olefins. For many applications, it is desirable for a polyolefin to have a high weight average molecular weight while having a relatively narrow molecular weight distribution. A high weight average molecular weight, when accompanied by a narrow molecular weight distribution, provides a polyolefin with high strength properties.
Traditional Ziegler-Natta catalysts systems—a transition metal compound co-catalyzed by an aluminum alkyl—are typically capable of producing polyolefins having a high molecular weight, but with a broad molecular weight distribution.
More recently a catalyst system has been developed wherein the transition metal compound has one or more cyclopentadienyl ring ligands (typically two)—such transition metal compound being referred to herein as a “metallocene”—which catalyzes the production of olefin monomers to polyolefins. Accordingly, titanocenes, zirconocenes and hafnocenes, have been utilized as the transition metal component in such “metallocene” containing catalyst system for the production of polyolefins and ethylene-alpha-olefin copolymers.
Catalysts that produce isotactic polyolefins are disclosed in U.S. Pat. No. 4,794,096. This patent discloses a chiral, stereorigid metallocene catalyst which is activated by an alumoxane cocatalyst and which is reported to polymerize olefins to isotactic polyolefin forms. Alumoxane co-catalyzed metallocene structures which have been reported to polymerize alpha-olefins stereoregularly include the ethylene bridged bis-indenyl and bis-tetrahydroindenyl titanium and zirconium (IV) catalysts. Such catalyst systems were synthesized and studied in Wild et al., J. Organomet. Chem. 232, 233-47 (1982), and were later reported in Ewen and Kaminsky et al., mentioned above, to polymerize alpha-olefins stereoregularly. Further reported in West German Off. DE 3443087A1 (1986), but without giving experimental verification, is that the bridge length of such stereorigid metallocenes can vary from a C1 to C4 hydrocarbon and the metallocene rings can be simple or bi-cyclic but must be asymmetric. When substituted or unsubstituted indenyl or tetrahydroindenyl based, these metallocenes are bridged in the “1-position” of the (hydro)indenyl ring, and are of C2 symmetry. Generally speaking, it is the C2 symmetric structure (also referred to as the d/l-enantiomers or racemic complexes) that produces isotactic poly-alpha-olefins. An alternate form is the Cs symmetric or meso form that produces atactic poly-alpha-olefins.

Thus, use of substituted bridged bis-indenyl and related ligands as starting materials makes it possible to obtain chiral ansa-metallocenes which are of great importance as transition metal components of active catalysts in the stereospecific polymerization of olefins. Variation of the ligand system, for example by means of substitution, enables the catalyst properties to be influenced in a targeted manner. This makes it possible to alter the polymer yield, the molecular weight distribution, the tacticity and the melting point of the polymers to the desired degree (Chem. Rev. 2000, vol. 100, no. 4; Metallocenes: Synthesis, Reactivity, Applications Ed. by A. Togni, R. L. Halterman.—Wiley-VCH, 1998). Bridged zirconocenes containing, as π ligands, indenyl radicals, which bear the bridge in position 1 and which preferably bear a hydrocarbon radical in position 2 and a hydrocarbon radical in position 4, have been found to be particularly highly active and stereoselective catalyst systems (European Patent Publication No. 0567970 A1; European Patent Publication No 0629632 A2). The ligand systems used for these highly active metallocenes are prepared from the corresponding indenes.
A number of processes comprising an inexpensive coupling reaction have been described for the preparation of certain aryl- and alkyl-substituted indenes and indanones (International Patent Publication No. WO 98/40331; U.S. Pat. No. 5,789,634; International Patent Publication No. WO 03/084904 A1). However, the synthesis of aryl-, alkyl-, and alkenyl-substituted bridged indenyl and related ligands has not been studied so far, though this methodology could provide an attractive route for obtaining libraries of the substituted metal complexes. Also, in the case of bridged indenyl and related ligands with an SiR2 bridge, Suzuki coupling reactions in protic medium will result in cleavage of such allylic silicon bridging group [Metal-catalyzed cross coupling reactions by Diederich, F.; Stang, P. J., Eds.; Wiley-VCH, 1998].
There is therefore a need for a simple and flexible process for preparing aryl-, alkyl-, and alkenyl-substituted bridged indenyl and related chelating ligands which are important intermediates for the preparation of active compounds and metallocene complexes.
According to the invention, it has now been found that substituted bridged indenyl and related chelating ligands containing halogen and/or sulfonate as leaving groups can be converted in a simple manner into substituted bridged indenyl and related chelating ligands which contain hydrocarbyl, substituted hydrocarbyl, halocarbyl, or substituted halocarbyl substituents bound via sp2 or sp3 center and which can be further used for the preparation of active compounds and metallocene complexes.